http://profdoc.um.ac.ir/articles/a/1015558.pdf

Fe-doped SnO2 transparent semi-conducting thin films deposited by spray pyrolysis technique: Thermoelectric and p-type conductivity properties

The compositional dependence of the thermal properties of SbxSe100−x melt quenched glasses (0.01 < x < 25 at.%) has been studied. Modulated temperature differential scanning calorimetry technique has been applied to determine the thermal properties of Se-rich SbxSe100−x chalcogenide glasses in the glass transition and crystallization regions. The reversing and non-reversing heat flows through the glass transformations were measured during both heating and cooling scans. Tg (glass transition), ΔHg (relaxation enthalpy), Cp (specific heat capacity), ΔCp (change in Cp at Tg), ΔHc (crystallization enthalpy), Tp (peak crystallization rate temperature) and Tc (crystallization onset temperature) which determine the thermal events in the glass were calculated from the experimental curves. Some of the structurally controlled parameters such as Tg, Cp, and Tc − Tg reveal local extrema when the Sb–Se glass system reaches 1 at.% Sb and 15 at.% Sb approximate concentrations, where the glass forming ability was also maximal. We discuss the results in terms of possible dimensional structural changes, `size effect' and local stoichiometry.

Thermal properties of SbxSe100−x glasses studied by modulated temperature differential scanning calorimetry

Structure and properties of thin films.

The electrical properties of Se2Sb2Te6 thin films are investigated using dc resistance, impedance spectroscopy and capacitance–voltage (C–V) measurements. The amorphous–crystalline transition temperature, Tc, is estimated to be 60 °C using dc resistance measurements. The impedance spectroscopy measurements are performed at different temperatures ranging from 25 to 95 °C. The impedance spectroscopy data give an estimation of the activation energy, Ev = 0.5 eV. The amorphous–crystalline interface is electrically characterized by measuring the capacitance of the film as a function of bias voltage at different temperatures ranging from 25 to 85 °C. The C–V measurements show temperature dependence and nonlinear behaviour of the capacitance with the applied bias voltages that could be attributed to the crystallization growth as the temperature gets close to Tc.

https://iopscience.iop.org/article/10.1088/0022-3727/41/21/215303/pdf

Electrical properties of Se2Sb2Te6 thin films

To understand the unique physical properties of Ga-Sb-Se glasses, high-resolution X-ray photoelectron spectroscopy (XPS) studies are performed on representative compositions within the glass-forming region The observed peaks in the valence band as well as in Ga, Sb, and Se core-level XPS spectra are related to the main structural building blocks of the covalent network On the basis of disproportionality equations and quantitative XPS analysis, the Se-Se-Se fragments are shown to exist in the glasses with 65 and 68 at% of Se, whereas the samples with lower Se content are shown to contain a significant concentration of Se-Se bonds instead Although the majority of Ga atoms are deemed to form fourfold coordinated units, the existence of Ga atoms in threefold coordination, those bonded to other metal, and forming Ga clusters of undissolved Ga are also plausible on the basis of Ga 3d XPS spectrum analysis Partial or full destruction of antimony selenide pyramids is found in glasses with low Se content

The structure of Ga‐Sb‐Se glasses by high‐resolution XPS

Thin films of different thicknesses in the range 400–1600 A have been vacuum deposited on clean glass substrates held at room temperature by very fast evaporation of the Se10Sb10Te80 bulk alloy. The thermoelectric power of these films has been measured as a function of temperature during heating and cooling cycles by the integral method. It is found that the thermoelectric power of these films is slightly different during the heating and the cooling cycles which is ascribed to slight reorientation of microcrystallites as also evidenced by x‐ray diffraction. It is further found that the thermoelectric power (at a constant temperature) is a function of film thickness; it varies nearly linearly with reciprocal thickness. From these data, the nature of carrier scattering in the films has been ascertained. From the energy‐dispersive x‐ray analysis patterns of the films the semiquantitative content of the constituent elements Sb, Se, and Te has been determined.

S. Aruna

Papers

Thermoelectric power of ternary semiconductor Se10Sb10Te80 thin films